Apparatus for recording and reproducing by the telegraphone principle.



H. R. STUART.

APPARATUS FOR RECORDING AND REPRODUGIN G BY THE TELEGRAPHONE PRINCIPLE.

APPLICATION FILED HABHZ, 1908.

Patented Qct.20,1908.

UNITED STA HARVE R. STUART, OF

APPARATUS FOR Specification of Letters Patent.

Es PATENT OFFICE;

WHEELIN G, WEST VIRGINIA. RECORDING AND REPRODUCIN G BY THE TELEGRAPHONE PRINCIPLE.

Patented Oct. 20, 1908.

Application filed March 2, 1908. Serial N 0. 418,690.

To all whom it may concern:

Be it known that I, HARVE R. STUART, a citizen of the United States,residing at Wheeling, in the county of Ohio and State of \Vest Virginia,have invented certain new and useful Improvements in Apparatus forRecording and Reproducing by the Telegraphone Principle, of Whichthefollowing is a full, clear, and exact description.

This invention relates to means for recording and reproducing speech,sounds and signals, under the telegraphone principle, and has for itsobject the provision of means whereby the record can. be stronglyimpressed upon the recording body so that the reproduction will becorrespondingly louder.

According 'to the principle of the telegraphone, the recording magnet isinfiuenced by the telephonic currents only, and the strength of therecord is therefore dependent upon the comparatively weak magnetismwhich such currents are capable of developing.

According to the present invention the electro-magnetism which is usedto record the message is derived from an independent source which may beeither a permanent magnet or an electromagnet, and this independentfield 'force is manipulated and directed so as to affect the recordingdisk, band or body by the mechanical movements of a diaphragm which arecreated by the voice or signal currents. In this Way the permanent orelectro-magnet may be a comparatively strong one, so that the availablepower for recording purposes is practically unlimited.

My invention is illustrated in the accompanying drawing in which theapparatus is illustrated somewhat conventionally.

Figure 1 is a front elevation of my improved apparatus, the parts beingshown in section; Fig. 2 is a si magnet system; Figs. 3 and 4 illustratemodifications of the anism.

The recording body of a telegraphone is illustrated by 1, being forconvenience in the form of a steel disk shown in edge View and supportedupon a centrally rotated axis 2. Mounted ad acent to the disk are twoelectromagnet coils 3 and 4, surrounding soft iron cores, which havesteel spring extensions 5 and 6, forming arts of the magaetic circuit.The cores 0 the two magnets ire connected by a back yoke 7, from the 1middle point of de elevation of the other to an adjusting screw 24.

fiu-x controlling mech- 'ing the tension which extends a bar of ironcores, and likewise having extension 9. These steel springs are ofsubstantially the same shape and resiliency and are connected togethernear their lower ends by a cross bar 10, of non-magnetic material, whichholds them in fixed relation to each other.

Between the extremities of the springs 5 and 9 is a soft iron bar orpiece 11, having a stem 12 projecting midway therefrom and resting atits extremity upon the face of the recording body 1, the extremity ofthis piece being reduced so as to cover only a small area of therecording body. Likewise between the extremities of the springs 9 and 6is a similarly T-shaped soft iron piece, indicated by 13 and 14, theextremity of which is also reduced and rests upon the face of therecording body 1. The two parts 12 and 14 serve as cores of electriccoils l5 and 16 respectively, and the entire system of coils 3, 4, 15,16, springs and cores, are mounted upon a single frame 17, so as tomovetogether in a radial or other suitable direction across the face ofthe disk 1 while the latter is in rotation. This movement of the magnetsystem may be controlled by a suit able feed screw which may operate inone of the openings 18 or 19 of th a guiding rod in the other, similarto any of the usual telegraphone or phonograph feeding mechanisms.

20 indicates an instrument containing a vibratory diaphragm 21, thecenter-of which is rigidly connected through link 22 with the rod 10, orsome other part of the structure 5, 9, 6, 10, so that the movement ofthe diaphragm will be communicated to the springs 5, 9, and 6, equallyand simultaneously. e opposite side of the springs spring 23, se- 10,and at the By adjustof this spring and the posi tion of the instrument20, the extremities of the springs 5, 9 and 6 are brought to neutralpositions or distances from the ends of the soft iron pieces 11 and 13.That is to say, the air gaps between the spring 6 and the piece 13,betwen 9 and 13, between 9 and 11, and between 5 and 11, are allnormally equal.

The instrument 20, as shown in Fig. 1, is merely a casing carrying thediaphragm, and having a mouthpiece into which speech or other sounds areto be directed. In Fig.

8, similar to the a steel spring cured at one end to the rod e frame,and

ioo

' pieces 11 and 13 will now 3, the instrument 20 is an ordinarytelephone 14.

receiver having the usual diaphragm which is moved by voice currentscoming from adistance over the circuit 25, either from being serviceablefor the purposes of the invention.

The two coils 3 and 4 are connected in circuit with a constant source ofelectricity 26, of considerable power, and the direction of winding, orflow of current through, the coils is such as to establish twoindependent fields of force, the middle core 8 and spring 9 being commonto both and having say an S polarity,whereas the outer cores or springs5 and 6 each have an N polarity. Thus one magnetic circuit is completedor nearly completed through the cross piece 11, while the other iscompleted or nearly completed through the cross piece 13, and so long asthe gaps between the springs and the cross ieces remain uniform, asdescribed, there will be no tendency of the lines of force in the twofields to take different courses.

In the operation of making a recor of a message or signals, the coils 15and 16 are not in use. That is to say, they are open circuited, and forthis purpose a small switch 27 is used, and placed in the open positionshown. Whenthe diaphragm 21 is vibrated by the sound waves enteringdirectly into the instrument 20, shown in Fig. 1, or coming from adistance to the instrument, shown in Fig. 3, the movements thereof areimparted to the springs 5, 9 and 6 uniformly and co incidently, amovement of the diaphragm to the left causing spring 6 to approach piece13, spring 9 to recede from spring and approach piece 11, and spring 5to recede from piece 11. induced by the two coils 3 and 4 which be, foretraveled uniformly across the respective be deflected because of thefact that the air gaps instead of being uniform are-now narrower at oneend of the iron piece and wider at the other, and lines of force whichalways take the path of least reluctance, will now travel from the endof spring 6 into the piece 13, thence through the core 14, then throughthe material of the recording body 1 to the other core 1.2, then throughthe piece 11, and across the narrow gap to the spring 9, the remainderof the circuit being the same as before. At the same instant, themagnetic circuit of the coil 3 will remain s bstantially the same asbefore, because no path of less reluctance is afforded. A record of themovement of the diaphragm to the left will therefore be impressed uponthe steel body, which will have a strength depending upon the strengthof the magnet 4, and the sum of the air gaps between 13 and 6, and 11and 9, this record being represented by a line of magnetism permanentlylocalized in the body 1 between the ends of the cores 12 and Thus thelines of force When the diaphragm 21 moves in the posite direction, orto the right, spring 6 recedes from 13, spring 9 approaches 13 andrecedes from 11, and spring 5 approaches 11. The conditions then beingreversed the lines of force from coil 3 are caused to travel from spring5 to piece 11, core 12, recording body 1, core 14, piece 13, and spring9, the lines from coil 6 continuing through 13 the same as normally.Thus the mo ement of the diaphragm the body 1 by a polarity opposite tothat of the movement to the left, and likewise of an intensity dependingupon the strength of the magnet and the sum of the air gaps between 5and 11 and 9 and 13. Since the magnets 3 and 4 are of constant and equalstrength, the strength of the recorded impulses with respect to eachother will be due to the differences in air gaps to which theirproduction is due, and this will be determined by the amplitude of therespective vibrations.

With this apparatusthe record of a message will be impressed upon thedisk 1 in a series of closely adjacent radial lines each of a lengthequal to the distance between the extremities of the bars 12 and 14. Itwill be seen that if the movable springs and the cross pieces constitutea switching device for the fields of force of the two constant magnets 3and 4, which device is controlled by the diaphragm. In reproducing therecord thus made, 'the'bars or pole pieces 12 and 14 are caused toretrace the same to the right is recorded in path on the disk as whenthe record was I made in accordance with the usual telegraphone method.The record may then be made audible in either of two ways: First,the-coils 15 and 16 may be connected in circuit either with the receiver28 or with a distant receiver through the circuit wires 29, by means ofthe switch 27 in which case the magnetic record will create currents inthe coils 15 and 16, which will aflect the receiver in circuit ,withthemand thus reproduce the record; or, second, the coils 15 and 16 may beleft open-circuited, in which case the successive polarities of themagnetic record will be alternately added to those of the coils 3 and 4,causing the system of springs 5, 9 and 6' to be moved alternately to theright and left by a process the converse of that by which the record wasoriginally made. The diaphragm 21 will therefore be correspondinglyvibrated and the record made audible in the instrument 20. If theinstrument 20 is substituted by a microphone, as indicated in Fig. 4,the instrument will act as a relay and the sounds reproduced at the moreor less distant station may be amplified through the additior of batteryin the microphone circuit. By this arrangement of the constant and independent field magnets 3 and 4, a magnetii flux of comparatively largepower is avail 901,397 v ,8, vable, and is readily manipulated orutilized lirations of the diaphra .will cause said 35 for the (purposeof making records by means ma eticscircuits to incIiidii/the recording Yof the elicate slprings 5, 9 and 6, or their bofy' substantially asdescribed.- equivalent, whic the voice currents or vi- 3. atelegraphone, thecombination of 5 brations are amply able to-move. Therea recordin body, two magnets ofconstant sult is that the recordmagnetism willbe force, an means whereby the vibrations 4o stronger andthe reproduction thereof comcorresponding to the message --or signalwill 1nensurately loud. Furthermore, in this cause said ma particulararrangement of the bars or-pole the rec'ordin E ody. a 10 pieces 12 and14 impin 'ngupon the record- 4.1 In a te egraphone, the combination ofets toalternately act uponf in body at considerab e distances from eacha recording body, two olep eces resting 5 0t er, the lines of forcetraverse larger areas thereon, two magnets --o constant force, a-

of the recording body aml will absorb cormagnetic switching deviceaalternately .res ondingly vmore ma et ism-, and this directing thefield of force of said me stay 15 without seriously decreasing thecapacity of through said pole pieces,and,means w erethe recording bodfor it isfound that "the by the impulses corresponding to the mes-' 5oturns of the slim pathtraced by the magsage or signal will actu te saidmagnetic nets upon the face of the disk can overlap switching evice. v vwithout interference so long as therecord 5. In a telegraphone,means-for reproduc},

of one turn is not exactly superposed upon 'ing the trecor that of thepreceding turn. prismg two magnetic circuits independent 55 7, Havingdescribed my invention, I claim: of that of the record means foralternately 1. In a telegraphone, the combination of "augmenting saidmagnetic circuits by the a recording body, a vibratory dia hragm,magnetic clrcuit of the record, anda vibratwo magnets of constant force,an means tory diaphragm influenced altern'atel by whereby the vibrationsof said dia hragm said two magnetic circuits, substantia y as 50 willalternately cause the lines of orce of described. 1 said magnets totraverse the recording body, In witness whereof, I. subscribe mysignasubstantially1 as deficribedil, Y b f ture, in the presence of twowitnesses.

2. In a te egra one, t e com ination o a recording body a vibratorydiaphragm, U

two magnets of constant force whose mag- Witnesses: v netic circuits arenormally exterior to the FREDERIG SCHAEFER, recording body, and meanswhereby the vi- -WM., 1). (looks.

in the recording body, com

